The present invention relates to a refrigerant distribution system, and more specifically, to a refrigerant distribution system having an evaporator that may be oriented such that the refrigerant flows horizontally.
Aircraft often use refrigerant systems to reject heat in galley cooling, electronics cooling and air conditioning. Refrigerant evaporators which boil off liquid refrigerant to cool off another media are susceptible to performance degradation due to gravitational orientation. In aircraft applications, it is not always possible to orient the evaporator in the optimal orientation with respect to gravity.
The optimal orientation in terms of performance is a vertical flow path, such that refrigerant flows against gravity. Less than optimal orientations allow the liquid refrigerant to separate from the vapor refrigerant resulting in liquid refrigerant distribution and performance less than what may be found with the optimal orientation.
To further complicate the problem, many refrigerant systems contain oil that is used to lubricate the compressor. A small portion of the oil tends to escape from the compressor and is circulated throughout the system. The oil must eventually be returned to the compressor to ensure proper lubrication and operation of the compressor.
At the evaporator, the liquid refrigerant evaporates and the oil separates from the refrigerant. The velocity in the evaporator must be large enough to overcome gravity and friction to return the oil to the compressor. In terms of oil return, the evaporator prefers to be oriented such that the refrigerant is flowing down with gravity so that gravity is actually assisting oil return. The optimal orientation for oil return and thermal performance are in conflict.
Many evaporators must compromise thermal performance due to orientation with respect to gravity in order to aid in oil return. This results in a heavier evaporator.
As can be seen, there is a need for a refrigerant distribution system that maximizes thermal performance of the evaporator when the evaporator is in a non-optimal thermal performance orientation.